Even though Gothic architecture, one of the most technologically complex sophisticated structural systems, has been interpreted by art and architectural historians since the nineteenth century, we still cannot entirely comprehend either the medieval builder's constructional technique and structural knowledge or the meaning of Gothic architectural elements. The major reason is that contemporaneous written documentation concerning design methods and constructional techniques of medieval architecture is lacking. In 1955, the Bibliotheque Nationale in Paris exhibited the sketchbook of the thirteenth century architect Villard do Honnecourt. After the exhibition, analysis on the architectural drawings of Villard's sketchbook had reported widely. Most of analysis on Villard, however, has been on his drawing and artistic style, and there has been very little published analysis of his profession and question on the author of the sketchbook. Thus, the purpose of this study is to investigate the characteristics of the sketchbook and identify the artist who drew it. The sketchbook poses a number of unsolved questions. There is no doubt that several hands have contributed some drawing with appropriate captions, particularly in the section devoted to the application of practical geometry to problems of masonry and carpentry. Scholars have assumed and revealed that it was not made by only one person, and it dealt too many different fields and styles. Through this study, the sketchbook drawings consist of five different styles and person (original painter, master1, master2, master3, and the last owner), and they, not Villard, just redrew the original drawings and bound the sketchbook. Therefore, Villard de Honnecourt was just a mentor of the sketchbook and he did not participate any writing and drawing in the sketchbook.